1. Field of the Invention
The present invention relates to novel histidine derivatives and to processes of preparing the histidine derivatives. The present invention also relates to cosmetic or dermatological compositions containing these compounds. The compounds may be used as agents for combating free radicals.
2. Discussion of the Background
Sunlight, heat, atmospheric pollution and, in particular, smoke and tobacco are known to bring about the formation of free radicals. They mainly originate from molecular oxygen. Mention may be made of the following free radicals:
singlet oxygen: highly oxidizing, highly toxic and with a very short lifetime, the product of the excitation of molecular oxygen by light photons; PA1 the superoxide radical anion: the product of the addition of an electron to oxygen, which can give rise to the production of highly reactive hydroxyl radicals; PA1 the hydroxyl radical: highly oxidizing and the most toxic to cells. PA1 n is an integer ranging from 0 to 5, PA1 n' is an integer ranging from 1 to 16, PA1 R represents a side chain of an amino acid, PA1 X represents a radical chosen from the radicals of formulae, read from left to right:" EQU --NH--CO--, --SO.sub.2, --NH--CO--CO--, --O--CO--CO--, PA1 R' represents an optionally hydroxylated, saturated or unsaturated, linear or branched C.sub.6 to C.sub.22 alkyl radical or a C.sub.6 to C.sub.22 aminoalkyl radical, the amine functional group optionally being protected in the acetamide form or substituted by one or two lower alkyl groups, PA1 Q.sup.+ represents H.sup.+ or an organic or inorganic carton, or an addition salt of a compound of formula (I) with an organic or inorganic acid. PA1 (1) R' denotes a saturated, linear or branched alkyl radical having from 8 to 18 carbon atoms, PA1 (2) n is an integer from 1 to 5, and/or PA1 (3) n' is an integer ranging from 1 to 11. PA1 N-octylaminocarbonyl-.beta.-alanyl-L-histidine, PA1 N-dodecylaminocarbonyl-.beta.-alanyl-L-histidine, PA1 N-octylsulphonyl-.beta.-alanyl-L-histidine, PA1 N-dodecylsulphonyl-.beta.-alanyl-L-histidine, and PA1 N-dodecylaminooxalyl-.beta.-alanyl-L-histidine.
The formation of these radical species results in particular in the oxidation of cutaneous lipids. Living cells, in particular those of the skin, scalp and certain mucous membranes, are particularly sensitive to these free radicals, which is reflected by an accelerated ageing of the skin, with a complexion lacking radiance and premature formation of wrinkles or fine lines, and also by a decrease in the vigor and a lacklustre appearance of the hair. It is therefore particularly important to protect the skin, hair and mucous membranes from these free radicals. It is known that some antioxidants can inhibit the formation of free radicals. Thus, carnosine, or N-p-alanyl-L-histidine, which is a natural dipeptide found in the muscles of numerous vertebrates, is known for its activity in combating free radicals, in particular in combating singlet oxygen (E. Decker and H. Faraji, JAOCS, Vol. 67, No. 10, 650-652, 1990). Its use as an antioxidizing agent or as an agent for combating free radicals in cosmetics is described in WO-A-92/09298. However, carnosine exhibits problems of decomposition on contact with the skin, caused by enzymes present in the skin and in particular proteases, which results in a significant loss in its activity.
Histidine derivatives are also known, such as, for example, the derivatives N-(4-amino-1-oxobutyl)-L-histidine, -(5-amino-1-oxopentyl)-L-histidine and N-(6-amino-1-oxohexyl)-L-histidine disclosed in RU2084457. However, due to their physicochemical nature, these histidine derivatives are unsatisfactory in protecting non-polar compounds from oxidation.
Accordingly, there remains a need for compounds which are useful for combating free radicals.